The intermediate horn contains preganglionic neurons located in which spinal segments?

• A. C1-C4
• B. T1-L2
• C. L4-L5
• D. S2-S4

Answer: (B)

The intermediate horn, or lateral horn, is where the preganglionic neurons of the sympathetic nervous system reside. This region is most prominent in the spinal cord from the upper thoracic (around T1) through the upper lumbar (up to L2) segments, forming the intermediolateral cell column. That’s why the preganglionic sympathetic neurons are located in those segments.

Other spinal levels don’t fit this pattern: the cervical area largely lacks a sizeable lateral horn for sympathetic neurons, the lower lumbar and sacral levels are not where the sympathetic preganglionic cells are housed (their parasympathetic counterparts are found in the sacral parasympathetic nucleus, S2–S4), and the explicit sympathetic preganglionic cell bodies aren’t organized there. So T1 through L2 best matches the location of the intermediolateral cell column that contains these neurons.